Footwear sole with leather fiber surface and method of making the same

ABSTRACT

A method of manufacturing a footwear sole includes providing a base sole, and performing an electrostatic flocking process to bond a leather material layer onto a portion of the base sole. The electrostatic flocking process includes the steps of applying an adhesive material to cover a surface of the base sole, providing a leather flock source, spraying electrically charged leather flock onto the adhesive covered surface of the base sole, and curing the base sole to bond the leather flock to the surface of the base sole. The method is described principally with respect to applying a leather material layer to a surface of a base sole, and the method may be employed to apply a leather material layer to shoe portions other than a surface of the base sole, such as a surface of the outer sole, insole, or inner sole, or a surface of a whole shoe.

RELATED APPLICATION

This application claims the benefit of priority of Chinese Utility Model Appl. No. 20120546984.X, filed Jun. 5, 2013, which is incorporated herein by reference.

FIELD OF INVENTION

The present invention relates generally to footwear and methods of making footwear, and particularly wear resistant footwear soles that are made in an environmentally friendly manner.

BACKGROUND OF THE INVENTION

Footwear soles typically are made of a variety of plastic or rubber materials. Such materials can be expensive and add significant cost to the final product. It would be desirable, therefore, to reduce the amount of the plastic or rubber materials that are utilized in manufacturing footwear soles. In addition, given the expense of such materials, various attempts have been made in the art to prolong the life of footwear soles. Footwear intended for outdoor use particularly is subject to hard surfaces (streets, trails, athletic surfaces, etc.) that can cause wear, and it would be desirable to enhance footwear soles in a manner that resists wear to prolong the useful life of the sole.

Leather footwear soles have been made in the art in an attempt to resist wear. In conventional manufacturing, a regenerated leather compound is formed by compounding leather scraps and a glue material. The regenerated leather compound is then pressed onto a base rubber or plastic sole using a sole press machine. The resultant footwear sole, however, has proven to be deficient. The sole manufactured in this manner lacks a genuine leather feel, and has little advantages in energy saving or being environmentally friendly. Pressed soles also tend to be subject to peeling off with use on hard surfaces, particularly outdoor surfaces, which can reduce the level or protection of the base rubber or plastic sole.

Also known in the art is a process known as electrostatic flocking, by which small particles of a fibrous material, referred to as “flock”, are coated onto an object. In a conventional electrostatic flocking process, the fibrous particles are negatively charged by ejecting the particles from a charging nozzle or through an electrostatic screen. An object to be coated is placed within a flocking chamber or housing that is subject to an electric field. The particular surface of the object to be coated may be provided with an adhesive material. The charged fibrous particles are directed by force and the electric field onto the surface to be coated, and the fibrous particles stick to such surface via the adhesive. The coated object then may be subjected to a heating or curing process that cures the adhesive to bond the fibrous particles to the object surface. As referenced above, however, pressed soles are the principle method of manufacturing leather footwear soles.

SUMMARY OF THE INVENTION

A need in the art exists for an improved footwear sole that overcomes one or more of the deficiencies of conventional footwear soles. In the present invention, a footwear sole includes a base sole padded with a leather material layer. The base sole may be formed of a suitable plastic or rubber material as are known in the art. The leather material layer is bonded to the base sole by an electrostatic flocking process.

In the flocking process, a surface of a base sole is coated with an adhesive material and placed within a housing or chamber of a flocking machine. Leather fiber materials, also referred to as leather flock, are ejected from a charging nozzle or through a charging screen to charge the leather flock. An electric field is applied to the flocking chamber to direct the leather flock onto the adhesive that has been applied to the base sole surface. The base sole, now containing the leather flock on at least the sole surface, is subjected to a curing process to cure the adhesive to bond the leather flock to the base sole, thereby forming the leather material layer. The resultant footwear sole, therefore, includes the base sole and the bonded leather material layer.

The footwear sole of the present invention has advantages over conventional configurations. The leather material layer reduces the amount of rubber or plastic material required to make the sole, thereby reducing costs. In addition, the leather material layer constitutes a protective layer that provides significant resistance to wear, which prolongs the life of the footwear sole. The protection is enhanced as compared to conventional pressed soles, as the flocking process provides a substantially stronger bond that is less subject to peeling.

An aspect of the invention, therefore, is a method of manufacturing a footwear sole. In exemplary embodiments, the method may include the steps of providing a base sole, and performing an electrostatic flocking process to bond a leather material layer onto at least a portion of the base sole. The step of performing the electrostatic flocking process may include the steps of applying an adhesive material to cover a surface of the base sole, providing a leather flock source, spraying electrically charged leather flock onto the adhesive covered surface of the base sole, and curing the base sole to bond the leather flock to the surface of the base sole.

Although the method is described principally with respect to applying a leather material layer to a surface of a base sole, the method may be applied to apply a leather material layer to shoe portions other than a surface of the base sole. For performing the flocking process, the adhesive may be applied to any surface of any portion of the shoe, such as, for example, a surface of at least one of the outer sole, insole, or inner sole, or a surface of a whole shoe. The flocking technique also may be employed to form a leather material layer on objects other than shoes.

These and further features of the present invention will be apparent with reference to the following description and attached drawings. In the description and drawings, particular embodiments of the invention have been disclosed in detail as being indicative of some of the ways in which the principles of the invention may be employed, but it is understood that the invention is not limited correspondingly in scope. Rather, the invention includes all changes, modifications and equivalents coming within the spirit and terms of the claims appended hereto. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing depicting a perspective view of a first exemplary footwear sole in accordance with embodiments of the present invention.

FIG. 2 is a drawing depicting a perspective view of a second exemplary footwear sole having a half sole and heel piece in accordance with embodiments of the present invention.

FIG. 3 is a drawing depicting an exemplary flocking apparatus that may be employed to manufacture a footwear sole in accordance with embodiments of the present invention.

FIG. 4 is a flowchart diagram depicting an exemplary method of manufacturing a footwear sole in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. It will be understood that the figures are not necessarily to scale.

FIG. 1 is a drawing depicting a perspective view of a first exemplary footwear sole 10 in accordance with embodiments of the present invention. The footwear sole 10 includes a base sole 12 and a leather material layer 14 formed on a bottom surface 15 the base sole 12. The base sole 12 may be made of a plastic or rubber like material as are known in the art as suitable for use in footwear soles. The leather material layer may be formed from a variety of leather based or leather like materials, including for example, real leather, imitation leather, leather scraps, leather pulp, or leather chaff and combinations thereof. Accordingly, as used herein the terms “leather” or “leather material” encompass all such leather based or leather like materials. As further described below, the leather material layer 14 is formed on the base sole 12 utilizing a flocking process. In exemplary embodiments, the leather material layer may have a thickness of between 0.2-8.0 mm.

FIG. 2 is a drawing depicting a perspective view of a second exemplary footwear sole 20 in accordance with with embodiments of the present invention. In this exemplary embodiment, the footwear sole 20 has a base sole that is divided. In particular, the base sole may be divided into a half sole 22 and a heel piece 24. The half sole 22 and heel piece 24 may be made of plastic or rubber materials comparably as the base sole 12 in the embodiment of FIG. 1. The footwear sole 20 further includes a half sole leather material layer 26 formed on a bottom surface 23 of the half sole 22, and a heel piece leather material layer 28 formed on a bottom surface 25 of the heel piece 24. The half sole and heel piece leather material layers 26 and 28 may be made of leather based or leather like materials comparably as the leather material layer 14 in the embodiment of FIG. 1. Again, as further described below, the leather material layers 26 and 28 are formed on the sole portions 22 and 24 utilizing a flocking process. In exemplary embodiments, the leather material layers may have a thickness of between 0.2-8.0 mm.

FIG. 3 is a drawing depicting an exemplary flocking apparatus 30 that may be employed to manufacture a footwear sole in accordance with embodiments of the present invention. The flocking apparatus 30 may include a flock source 32, such as a storage container or hopper containing the leather flock. The flock is driven under pressure of compressed air through a nozzle 34. In exemplary embodiments, the nozzle 34 is a charging nozzle that is charged by a power source (not shown). The charging nozzle electrically charges the particles of the leather flock, typically negatively charged, prior to or as the leather flock particles are ejected from the nozzle. Alternatively, the nozzle may eject the flock particles through a charging screen 36, also referred to in the art as static generator net, as seen in FIG. 3 The charging screen is charged by the power source to electrically charge the flock particles as the particles pass through the screen.

The flocking apparatus 30 further may include a flocking chamber 38 into which the article to be flocked is place, such as the base sole 12 (or divided sole 22/24). The flocking chamber may include opposite electrodes 40 and 42 for generating an electric field within the flocking chamber 38. The electric field, in combination with the pressure from the nozzle, operates to distribute the flock sprayed from the nozzle over the base sole surface being coated. As referenced above, in a flocking process, the surface to be coated, in this case the surface of the base sole, is covered with an adhesive to which the flock sticks. The adhesive then may be subjected to a heating process to cure the adhesive, thereby bonding the flock to the surface being coated, again in this case the surface of the base sole. Accordingly, in exemplary embodiments, the flocking chamber 38 also may be operable as a heating chamber or oven to perform the curing process. Alternatively, the sole with the coating of flock/adhesive may be removed from the flocking chamber and cured in a separate heating chamber or oven.

FIG. 4 is a flowchart diagram depicting an exemplary method of manufacturing a footwear sole in accordance with embodiments of the present invention. The method in particular employs a flocking process that bonds a leather material layer onto a base sole. Although the exemplary method is described as a specific order of executing functional logic steps, the order of executing the steps may be changed relative to the order described. Also, two or more steps described in succession may be executed concurrently or with partial concurrence. It is understood that all such variations are within the scope of the present invention.

The method may begin at step 100 at which a base sole is provided. The base sole may be a unitary base sole such as the base sole 12 of FIG. 1, or a divided base sole such as the base sole of FIG. 2 including the half sole 22 and heel piece 24. The remaining steps constitute a flocking process to bond a leather material layer onto the base sole.

At step 110, an adhesive material is applied to cover a surface of the base sole, and typically a bottom surface of the base sole so as to provide wear protection. The adhesive may be an environmentally friendly water-based glue or white latex material, and may be combined with a suitable stabilizer, bonding agents, curing agents, and like additives to improve adhesion as are known in the art.

At step 120, a leather flock source is provided. The flock may be produced by grinding leather waste or scrap of the leather like or leather based materials described previously, and then extracting the fibrous leather particles. As referenced above, the present invention is not limited to any particular leather material. The leather material layer may be formed from a variety of leather based or leather like materials, including for example, real leather, imitation leather, leather scraps, leather pulp, or leather chaff and combinations thereof. The leather flock also may be colored or dyed as desired for appearance. Suitable particle size for the leather flock may be from 40-100 μm.

At step 130, electrically charged leather flock is sprayed on the adhesive-covered surface of the base sole. In exemplary embodiments, a high pressure flocking technique is employed by spraying the leather flock from a high pressure nozzle or air gun. A suitable ejection pressure may be 4-8 kg. The leather flock may be electrically charged by utilizing a charging nozzle, or by spraying the flock through a charging screen or static generator net. An electric field applied to the flocking chamber, in combination with the pressure from the nozzle or air gun spray, operates to distribute the leather flock sprayed from the nozzle/air gun over the base sole surface being coated. At step 140, the leather flock coated base sole is cured, thereby bonding the leather flock to the bottom surface of the base sole. Oven curing temperature can be set by known techniques based on the specific sole and flock materials and configurations being employed.

The use of electrostatic flocking enhances the flocking strength, firmness of the resultant leather material layer, and uniformity of appearance. Soles manufactured by the methods of the present invention can satisfy significant wear standards as measured by conventional abrasion and tensile tests. Depending upon the precise thickness of the resultant leather material layer and the specific leather materials used, according to a range of product standards, the sole can meet 5000 to 50,000 abrasion repetitions. Tensile strengths can range from 15-21 kg.

The footwear sole manufacturing process of the present invention has significant advantages over conventional processes. The leather material layer formed by electrostatic flocking has a superior leather feel and appearance as compared to pressed soles. The leather material layer reduces the amount of rubber or plastic material required to make the sole, thereby reducing costs. In addition, the leather material layer constitutes a protective layer that provides significant resistance to wear, which prolongs the life of the footwear sole. The protection is enhanced as compared to conventional pressed soles, as the flocking process provides a substantially stronger bond that is less subject to peeling.

In the method above, the leather material layer is formed by the flocking process on the entire bottom surface of the base sole. This, however, need not be the case. The leather material layer may be formed on only portions of the base sole that may be most subject to wear. For example, the leather material layer may be formed on portions of the base sole corresponding to the ball of the feet and/or heels, where most of the stepping force is concentrated. When the base sole itself is divided between a half sole and heel piece, different leather material layers may be provided on each portion, and/or with different with separate flocking processes. In other words, a first leather material layer may be bonded to the half sole and a second leather material layer may be bonded to the heel portion. Alternatively, the leather material layer may be provided on only one or the other of the half sole portion or heel portion.

In addition, the process of this invention may be applied to form a leather material layer on shoe portions other than a bottom surface of the base sole. For performing the flocking process, the adhesive may be applied to any surface of any portion of the shoe, such as, for example, a surface of at least one of the outer sole, insole, or inner sole, or a surface of a whole shoe. The flocking technique also may be employed to form a leather material layer on objects other than shoes.

An aspect of the invention, therefore, is a method of manufacturing a footwear sole. In exemplary embodiments, the method of manufacturing a footwear sole includes the steps of providing a base sole, and performing an electrostatic flocking process to bond a leather material layer onto at least a portion of the base sole.

In an exemplary embodiment of the method of manufacturing a footwear sole, the step of performing the electrostatic flocking process includes the steps of applying an adhesive material to cover a surface of the base sole; providing a leather flock source; spraying electrically charged leather flock onto the adhesive covered surface of the base sole; and curing the base sole to bond the leather flock to the surface of the base sole.

In an exemplary embodiment of the method of manufacturing a footwear sole, the adhesive material comprises one of a water based glue or latex material.

In an exemplary embodiment of the method of manufacturing a footwear sole, the adhesive material further includes at least one of a stabilizer, bonding agent, or curing agent additive.

In an exemplary embodiment of the method of manufacturing a footwear sole, the step of providing a leather flock source comprises grinding a leather scrap material and extracting fibrous leather particles.

In an exemplary embodiment of the method of manufacturing a footwear sole, a particle size of the leather flock ranges from 40-100 μm.

In an exemplary embodiment of the method of manufacturing a footwear sole, the leather flock is electrically charged by spraying the leather flock from a charging nozzle.

In an exemplary embodiment of the method of manufacturing a footwear sole, the leather flock is electrically charged by spraying the leather flock through one of a charging screen or a static generator net.

In an exemplary embodiment of the method of manufacturing a footwear sole, the method further includes providing the base sole in a flocking chamber, and applying an electric field to the flocking chamber to distribute the leather flock onto the adhesive covered surface of the base sole.

In an exemplary embodiment of the method of manufacturing a footwear sole, the leather flock is sprayed an at ejection pressure of 4-8 kg.

In an exemplary embodiment of the method of manufacturing a footwear sole, the leather material layer is bonded onto an entire bottom surface of the base sole.

In an exemplary embodiment of the method of manufacturing a footwear sole, the leather material layer is bonded onto a portion of a bottom surface of the base sole less than the entire bottom surface.

In an exemplary embodiment of the method of manufacturing a footwear sole, the base sole comprises a half sole and a heel portion, and a first leather material layer is bonded to the half sole and a second leather material layer is bonded to the heel portion.

Another aspect of the invention is a method of manufacturing a shoe. In exemplary embodiments, the method of manufacturing a shoe includes the steps of providing a shoe, and performing an electrostatic flocking process to bond a leather material layer onto at least a portion of the shoe.

In an exemplary embodiment of the method of manufacturing a shoe, the step of performing the electrostatic flocking process includes the steps of: applying an adhesive material to cover a surface of the shoe; providing a leather flock source; spraying electrically charged leather flock onto the adhesive covered surface of the shoe; and curing the shoe to bond the leather flock to the surface of the shoe.

In an exemplary embodiment of the method of manufacturing a shoe, the adhesive material is applied to a surface of at least one of the outer sole, insole, or inner sole, or a surface of a whole shoe.

Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application. 

What is claimed is:
 1. A method of manufacturing a footwear sole comprising the steps of: providing a base sole; and performing an electrostatic flocking process to bond a leather material layer onto at least a portion of the base sole.
 2. The method of claim 1, wherein the step of performing the electrostatic flocking process comprises the steps of: applying an adhesive material to cover a surface of the base sole; providing a leather flock source; spraying electrically charged leather flock onto the adhesive covered surface of the base sole; and curing the base sole to bond the leather flock to the surface of the base sole.
 3. The method of claim 2, wherein the adhesive material comprises one of a water based glue or latex material.
 4. The method of claim 3, wherein the adhesive material further includes at least one of a stabilizer, bonding agent, or curing agent additive.
 5. The method of claim 2, wherein the step of providing a leather flock source comprises grinding a leather scrap material and extracting fibrous leather particles.
 6. The method of claim 2, wherein a particle size of the leather flock ranges from 40-100 μm.
 7. The method of claim 2, wherein the leather flock is electrically charged by spraying the leather flock from a charging nozzle.
 8. The method of claim 2, wherein the leather flock is electrically charged by spraying the leather flock through one of a charging screen or a static generator net.
 9. The method of claim 2, further comprising: providing the base sole in a flocking chamber; and applying an electric field to the flocking chamber to distribute the leather flock onto the adhesive covered surface of the base sole.
 10. The method of claim 2, wherein the leather flock is sprayed an at ejection pressure of 4-8 kg.
 11. The method of claim 1, wherein the leather material layer is bonded onto an entire bottom surface of the base sole.
 12. The method of claim 1, wherein the leather material layer is bonded onto a portion of a bottom surface of the base sole less than the entire bottom surface.
 13. The method of claim 1, wherein the base sole comprises a half sole and a heel portion; and a first leather material layer is bonded to the half sole and a second leather material layer is bonded to the heel portion.
 14. A method of manufacturing a shoe comprising the steps of: providing a shoe; and performing an electrostatic flocking process to bond a leather material layer onto at least a portion of the shoe.
 15. The method of claim 14, wherein the step of performing the electrostatic flocking process comprises the steps of: applying an adhesive material to cover a surface of the shoe; providing a leather flock source; spraying electrically charged leather flock onto the adhesive covered surface of the shoe; and curing the shoe to bond the leather flock to the surface of the shoe.
 16. The method of claim 15, wherein the adhesive material is applied to a surface of at least one of the outer sole, insole, or inner sole, or a surface of a whole shoe. 